Segmental commutator rings are frequently made by starting with a blank of rectangular plan view, that is, a strip of commutator material, typically copper, which is then formed into a cylindrical tube. It is known to shape such an element into a ring-shaped blank with parallel oppositely located ends which define a gap therebetween. This blank is then placed in a cold-flow press which has a press or stamp part with projecting teeth to define grooves in the subsequent commutator ring. The press, also, forms a flange at the end of the essentially cylindrical blank to provide connecting paths or tabs for the windings of a rotating armature, to be connected to the commutator segments. The grooves, which separate the commutator segments, remain connected by thin convex connecting ribs, later separated to separate the commutator segments, electrically, from each other, for example after the ring has been assembled on an insulating hub.